A comparative analysis of bacterial flora and proximate composition of mud crab (Scylla serrata,Forsskal 1775) collected from different local markets of Dhaka city

Abstract

The present study was carried out to investigate the presence of bacterial flora and proximate composition of mud crab (Scylla serrata) meat from the local markets (Mohakhali, Karwan bazar, Farmgate, Basabo and Agora super shop) of Dhaka city. The densities (cfu/g) of total bacterial count (TBC), total coliform (TC), fecal coliform (FC), total Salmonella spp. and Shigella spp. (SS), total E. coli, total Staphylococcusspp. and total Vibriospp. like colonies were counted. Moisture, ash, protein and lipid contents were also determined for the samples of each market. TC, FC, SS, E. coil, and Vibrio spp. were detected in most of the samples except the frozen ones from Agora super shop. The samples from Basabo and Karwan bazar had much higher bacterial load than the others. The highest TBC counts were observed in the samples from Karwan bazar (38.1 ± 1.20 x104cfu/g) and the lowest were from Agora super shop (4.48 ± 0.26 x104cfu/g). The total Vibriospp. counts were found only in two markets; Farmgate and Basabo. The total E. coli countsranged from 1.25± 0.02 x104cfu/gto 4.33± 0.56x104cfu/g. The Salmonella, Shigella (SS) counts variedbetween3.95± 0.28 x104cfu/g for Karwan bazarand 16.76±1.26x104cfu/g for Basabo.Total Staphylococcus spp. counts ranged between 14.4± 1.1 x104cfu/gand 20.01± 1.94 x104cfu/g for normal crab samples and 0.37±0.025x104cfu/g for frozen samples. A total of 47 isolates were recovered from the samples and 10 generawere identified asBacillus,Citrobacter,Alcaligens,Salmonella,Shigella,Vibrio,Escherichia,Klebsiella,Staphylococcus and Enterobacter. Nearly similar nutritional compositions were found in the live crab samples. Whereas,much lower moisture content with higher ash, protein and lipid contents were observed in frozen samples. The results of this study showed that the bacterial load was significantly higher in live crab samples than the frozen ones which arevery useful to evaluate the safety of mud crab for human consumption.Consumption of normal crabs from above mentioned markets can lead to food borne diseases of human, whether the frozen samples can be considered as much safer. This study also revealed that mud crabs can be an alternative source of protein (excluding the bacterial hazards) to the traditional protein sources as its protein content is high.